A LED backlight for a liquid crystal display (LCD), having a boost circuit for boosting in different display modes, an input voltage for operating each LED in a current display mode. The display modes include 2D and 3D display modes. A plurality of LED strings which are connected in parallel, wherein each LED string having a predetermined number of LEDs connected in series and receives the working voltage required for operating from the boost circuit. A current regulation circuit for regulating in the different display modes, with current flowing through each LED string, such that a ratio of the current flowing through each LED string in the 3D display mode and in the 2D display mode is changed. A controller provides a driving signal to drive the boost circuit, and provides different voltages to the current regulation circuit in the different display modes.